As the OP, I have found complete info on this problem to be coming slowly. These master cylinders are on a lot of brands. Please read the whole thread before jumping to conclusions. As with problems like this, the easy path is making POS and 'can never be trusted again' comments. The mature path is focusing on identifying the problem and the solution and moving on. Often the difference between problems and no problems in manufactured parts is very subtle. There is all sorts of detail farther down this thread. I found out today why there was a run of bad BrakTec rear master cylinders. Not sure if front master cylinder involved too (yes it is). I was talking to Stu Preston about them and he said when he was vising the factory, they showed him what the problem was. Having had problems like these in my manufacturing and design days, I had to chuckle and shake my head. The problem was said to be in the diameter of the fluid refresh hole. I don't have the exact details, but the early Brake Tech master cylinders was reported to have a bit too large fluid refresh hole, and when the cup seal was passing over that hole from its resting position on the way to pressurizing the brakes, apparently the seal lips would pucker back into the hole and get nipped. The fix was making that hole just a bit smaller! I found out later there was more to this than hole diameter. The edge condition of the holes where they meet the cylinder may be just as much or more important. AJP went kaput sometime around `11 or `12, then in a scramble to secure supply Gas Gas tapped Formula. Formula make the best forks in my opinion, but their brakes have had some problems. Then came Brake Tech, bringing back the AJP-type designs but with updates. Perhaps AJP actually became Brake Tech... I don't know. But whatever happened, a nuance of engineering was missed, and they burned themselves. If anyone knows more on this, please chime in. It's hard to make a big hole smaller in a honed and hard coated cast aluminum, but perhaps if a person was good at machining the hole could be plugged and re drilled and the bore honed? There must be a number of these bad ones out there that just need a smaller fluid refresh hole? Not the whole story - read on.